Melatonin and Infection Altered miR-294, miR-30e, and miR-302d Impacting on , , and 2 Expression.

Leishmaniases are neglected diseases that cause a large spectrum of clinical manifestations, from cutaneous to visceral lesions. The initial steps of the inflammatory response involve the phagocytosis of and the parasite replication inside the macrophage phagolysosome. Melatonin, the darkness-signaling hormone, is involved in modulation of macrophage activation during infectious diseases, controlling the inflammatory response against parasites.

Arginase expression modulates nitric oxide production in Leishmania (Leishmania) amazonensis.

Background: Arginase is an enzyme that converts L-arginine to urea and L-ornithine, an essential substrate for the polyamine pathway supporting Leishmania (Leishmania) amazonensis replication and its survival in the mammalian host. L-arginine is also the substrate of macrophage nitric oxide synthase 2 (NOS2) to produce nitric oxide (NO) that kills the parasite. This competition can define the fate of Leishmania infection.

L-arginine availability and arginase activity: Characterization of amino acid permease 3 in Leishmania amazonensis.

Background: Leishmania uses the amino acid L-arginine as a substrate for arginase, enzyme that produces urea and ornithine, last precursor of polyamine pathway. This pathway is used by the parasite to replicate and it is essential to establish the infection in the mammalian host. L-arginine is not synthesized by the parasite, so its uptake occurs through the amino acid permease 3 (AAP3).